The three medications being evaluated in this trial include tiagabine, sertraline, and donepzil. Tiagabine is hypothesized to interfere with glutamatergic cocaine mechanisms relevant to addiction. Sertraline is a potent and selective inhibitor of neuronal 5-HT reuptake, which may modulate the reinforcing and cueing effects of cocaine. Donepezil is hypothesized to interfere with cholinergic cocaine mechanisms relevant to addiction.